Light-sensitive silver halide photographic material

ABSTRACT

An improved process for preparing a light-sensitive silver halide photographic material and a photographic material produced thereby are disclosed which comprises incorporating, into a gelatinous photographic emulsion, liquid-containing fine capsules which are obtained by preparing an aqueous liquid composed mainly of a first reactant and a water-immiscible liquid composed mainly of a first reactant and a water-immiscible liquid composed mainly of a second reactant capable of forming a polymer by reaction with said first reactant, and dispersing as fine drops either one of said liquids into the other liquid to form a polymer according to polycondensation reaction of said first reactant with said second reactant which takes place at the interface between the two liquid, so that the surfaces of said fine drops are coated with the thus formed polymer.

United States Patent Suga et al. Oct. 1, 1974 [54] LIGHT-SENSITIVE SILVER HALIDE 3,427,160 2/1969 McCune, Jr. 96/29 R PHOTOGRAPHIC MATERIAL glciunekjrl. er er e a [75] Inventors: Tsuneo Suga; Sh ob Korematsu, 3,694,253 9/1972 Gerber CI al 117/93 both of Tokyo; Masaru Kanbe, 3,697,279 10/1972 Rogers et al 96/77 Yamanashi; Akihiko Miyamoto, Tokyo, all of Japan Primary Examiner-Ronald H. Smith [73] Assignee: Konishiroku Photo Industry Co., Afls'stam Exammer lfonso Sum 9 Ltd Tokyo Japan Attorney, Agent, or FzrmB1erman & Blerman [22] Filed: Aug. 23, 1972 [57] ABSTCT [21] Appl' 283052 An improved process for preparing a light-sensitive silver halide photographic material and a photo [30] F i A li ti P i it D t graphic material produced thereby are disclosed 27 1971 Japan 4665130 which comprises incorporating, into a gelatinous photographic emulsion, liquid-containing fine capsules 52 US. Cl 96/114 96/50 PL 96/67 which are Obtained by Preparing News quid 96/82 96/84R 96/84 UV96/87 A composed mainly of a first reactant and a water- 66/114 4 96/l 14 immiscible liquid composed mainly of a first reactant 51 Int. Cl G036 1/02 6036 1/84 and a water-immiscible quid mainly Of a [58] Field of Search 96/114.4 i14 s5 74 Second reactamcapable offormingapdymer by 96/12O 3 84 R 84 UV tion with said first reactant, and dispersing as fine 50 L 17/21 drops either one of said liquids into the other liquid to form a polymer according to polycondensation reac- [56] References Cited tion of said first reactant with said second reactant which takes place at the interface between the two liq- 2 284 877 :A T PATENTS 96/74 uid, so that the surfaces of said fine drops are coated artmez 'th th th f d l 2,907,682 l0/l959 Eichel l ll7/2l WI 6 us orme p0 ymer 3,276,869 l0/l966 McCune, Jr 96/3 5 Claims, N0 Drawings LIGHT-SENSITIVE SILVER HALIDE PHOTOGRAPHIC MATERIAL This invention relates to a light-sensitive silver halide photographic material containing a novel photographic softener.

Heretofore, gelatin has chiefly been used as a dispersion medium for silver halide photographic emulsions. Gelatin has many advantages. That is to say,'gelatin is not only an excellent dispersion medium for silver halide grains and developed black silver but also has a gelling ability and hence is successfully usable for preparation of light-sensitive photographic films. Further, it makes possible the production of films high in transparency, and gelatinous emulsion layers obtained by use of gelatin are quickly penetrable with processing solutions and hence are preferable for development, fixing, washing, and the like photographic treatments. On the a other hand, however, gelatinous coatings have such drawbacks that they are brittle and easily cracked at a low humidity, and the light-sensitive materials bearing said coatings are low in elasticity and hence tend to suffer from curling.

In order to overcome the above drawbacks, it was a common practice to incorporate various softeners into gelatin coatings. As the conventional softeners, there are such water-soluble high molecular compounds (other than gelatin) as polyacrylamides and polyvinyl alcohols; such low molecular compounds as glycerin and hexylene glycol which are generally called wetting agents; oil drops of such high boiling solvents as tricresyl phosphate and dibutyl phthalate; and latex particles.

However, the water-soluble high molecular compounds are not well miscible with gelatin and hence are limited in amount to be added to gelatin to make it difficult to impart sufficient elasticity to gelatinous coatings, and the wetting agents tend to make gelatinous coatings tacky and tend to flow out during a series of photographic treatments and are deprived of their effects. In order to uniformly disperse in gelatinous coatings the high boiling solvents, large quantities of surface active agents are required which bring about, in most cases, detrimental effects in the photographic properties of the resulting light-sensitive materials. The latex particles frequently contain catalysts and surface active agents which have been used for the preparation thereof. These residual catalysts and surface active agents are not completely removable, and hence give detrimental effects to the photographic properties of light-sensitive photographic materials, and, in some cases, they become tacky to form agglomerates. Thus, no satisfactory softeners for gelatin have yet been obtained.

The object of the present invention is to provide an excellent and novelphotographic softener having no such drawbacks as mentioned above, and to provide a curling-free excellent light-sensitive silver halide photographic material having elastic photographic coatings incorporated with said softener.

The above-mentioned object of the present invention can be accomplished by using as the photographic softener a mixture of fine particles of a liquid which have been formed into micro-capsules according to an interfacial polymerization method. That is, we have found that the above object can be achieved by using as the photographic softener a mixture of liquid-containing fine capsules of less than about 1 micron in average particle size which is obtained by using an aqueous liquid composed mainly of a first reactant and a waterincompatible liquid composed mainly of a second reactant capable of forming a polymer by reaction with said first reactant, and dispersing as fine drops either one of said liquids into the other liquid to form a polymer according to the polycondensation reaction of said first reactant with said second reactant which takes place at the interface between the two liquids, so that the surfaces of said fine drops are coated with the thus formed polymer.

The production of micro-capsules according to an interfacial polymerization method, in which either one of an aqueous liquid and a water-incompatible liquid is dispersed as fine drops into the other liquid and the surfaces of said fine drops are coated with a polymer formed by a polycondensation reaction taking place at the interface between said two liquids, can be conducted according to any of the processes disclosed in Japanese Patent Publication Nos. 19,574/63, 446/67, 771/67, 2,882/67, 2,883/67, 8,693/67, 8,923/67, 9,654/67, ll,344/67, 17,655/68, 11,772/67, 20,885/ and l8,l27/7l.

In a process for producing micro-capsules according to interfacial polymerization, in which two substances capable of forming an insoluble polymer film by reaction with each other are individually dissolved in each of an aqueous liquid such as water, alkanolamine or polyhydric alcohol and a water-incompatible liquid such as fatty acid, mineral oil, organic solvent, plasticizer or oil-soluble surface active agent, and fine drops of either one of the two liquids are dispersed into the other liquid to form an insoluble polymer film at the interface between the two liquids thereby coating the fine drops with the thus formed film, no liquid is particularly required as solvent so far as the reactants themselves are liquid.

For example, in case micro-capsules of a polyurea are to be obtained, a solution of polyisocyanate as one reactant in such a solvent as toluene or dibutyl phthalate is used as the water-incompatible liquid, and a solution of diamine as the other reactant in such a solvent as water or a mixture thereof with glycerin is used as the aqueous liquid. Since the polyisocyanate forms a polyurea not only by reaction with diamine but also by reaction with water, the diamine in the aqueous liquid is not required to be used.

As substances for forming capsule films, there may be used, in addition to polyureas, many such substances as epoxy resins, phenol-formalin resins, polyamides, polyesters and reaction products of polyvinyl alcohols with benzaldehyde. In order to make the film of capsules higher in density thereby enhancing the coating ability thereof, it is preferable to use a compound having a large number of functional groups in place of a compound having a small number of reactive groups. In some cases, it is possible to use a compound which has been polymerized to a certain extent.

In addition to such known processes as mentioned above, it is, of course, possible to utilize a process in which several reactants are used in combination to produce more reinforced multiple micro-capsules, and a process in which a non-diffusing substance high in compatibility with the liquid contained in micro-capsules is incorporated into said liquid in order to prevent the liquid from flowing out.

The first and second reactants, which are used for preparation of the liquid-containing micro-capsules of the present invention, may have individually been dissolved in a liquid incompatible with the aqueous liquid and water. Alternatively, either one of the reactants may have previously been dissolved in the liquid, which is to be dispersed as fine drops, and the said liquid is dispersed as fine drops, and then the other reactant is added to the resulting dispersion to carry out polycondensation reaction at the interface between the two liquids. Thus the time of addition of the two reactants used in the present invention is not limited at all but can be selected optionally.

Each of the first and second reactants used in the present invention does not always indicate only one reactant but may be a suitable combination of two or more compounds. Thus, there is involved the case where a combination of two compounds is used as the first reactant and a combination of two compounds is used as the second reactant. In such case, however, the compounds used as the constituents of the first or second reactant should be those which do not polycondense with each other. When such combination of two or more reactants is used, it is possible to control the properties of the resulting polymer film.

The micro-capsules, which are obtained according to the above-mentioned interfacial polymerization method, have homogeneous, thin and tough polymer film walls and are soft and elastic fine globular particles, so that a mixture of such micro-capsules can be used as a photographic softener having excellent properties. That is, the softener according to the present in-.

vention is composed of micro-capsules containing a liquid, so that when an external force is applied thereto, the stress can be alleviated by deformation of the micro-capsules. The softener of the present invention is far more effective in said stress-alleviating property than any of the conventional softeners. Further, when the softener of the present invention is used, there are brought about no such conventional drawbacks encountered in dispersing oil drops of a high boiling solvent that the drops are deprived of their effect by vaporization, agglomerate together to form large particles in gelatin coatings, or dissolve a compound surrounding the drops.

The softener particles according to the present invention can be prepared while optionally controlling the particle size thereof, the refractive index of the liquid contained in the capsules, and the thickness and refractive index of film walls of the capsules. Accordingly, the softener particles can be suitably controlled in refractive index and transparency, and thus are far more advantageous than'the conventional softeners in the case where they are intended to be incorporated into light-sensitive photographic materials. For example, when the softener particles are reduced in particle size to less than one-severals of a micron, a light-sensitive silver halide photographic material incorporated with the softener particles can sufficiently be made transparent. Further, when the refractive index of the liquid contained in the capsules is made identical with that of the gelatin film, the transparency can be increased.

For preparation of the photographic softener of the present invention, the micro-capsulation should be effected according to interfacial polymerization method for such reasons that the said method is more advantageous than other micro-capsulation methods, e.g., in

- particles are coated with a wall material supplied from only the exterior of the particles. According to this method, therefore, each particle is difficultly encapsulated and several particles agglomerate together to give no other particles than those having a particle size of more than 1 11. Further, the micro-capsules obtained according to the above method are undesirably low in elasticity. Likewise, micro-capsules obtained according to said in situ polymerization method, curing-coatingin-liquid method, meltable dispersion method, dryingin-water method and spray drying method are not only large in particle size but also limited in kind of liquid to be contained therein and hence are not preferable as photographic softeners.

In order to be used as softeners for gelatin coatings of light-sensitive silver halide photographic materials, particles having an average particle size of less than 1 micron are preferable. Among the layers constituting a light-sensitive silver halide photographic material, some are as thin as about 1 micron. Particularly, the protective layer and inter layer of said photographic material and the emulsion layer of a multi-color photographic material are extremely thin. In incorporating into such thin layer, softener particles which are excessively large in particle size are difficultly distributed uniformly. Further, in order to display softening effect, individual softener particles are required to have isotropy. In the case of softener particles excessively large in particle size, the said property cannot be retained. Moreover, particles excessively large in size cover the lower silver halide layer at the time of exposure to injure the resulting image in some cases. In order not to bring about such drawbacks as above, softener particles of less than 1 micron in average particle size are used in the present invention.

According to the aforesaid method adopted in the present invention, it is possible to produce liquidcontaining micro-capsules uniform in particle size. Micro-capsules having a particle size within the range from 0.1 micron to a visible size can be produced. In the present invention, however, micro-capsules of less than 1 micron in particle size is produced, as mentioned previously, and a mixture of said micro-capsules is used as the photographic softener.

In order to incorporate as the softener a mixture of the liquid-containing micro-capsules of the present invention into a light-sensitive silver halide photographic material, the micro-capsules are dispersed in an aqueous high polymer solution of gelatin or polyvinyl alcohol or in an aqueous solution by use of a surface active agent, and the resulting dispersion is incorporated into a solution for forming a layer of a photographic material such as silver halide emulsion layer, protective layer, inter layer or backing layer. The amount of the softener to be incorporated is suitably decided according to the properties of the micro-capsules used and the kind of the layer into which the softener is to be incorporated, but is preferably within the range from to 30 percent by weight based on the weight of gelatin.

The photographic softener of the present invention may contain optional substances in the encapsulated liquid. That is, the softener may contain any of inorganic compounds such as sodium chloride, potassium bromide, potassium iodide, magnesium sulfate, sodium carbonate, sodium hydroxide and phosphoric acid, and various additives for light-sensitive photographic materials such as antistatic agents (e.g., acyl hydrazinium salts and ethylene oxide addition polymers of phenolformalin resins), ultraviolet absorbers (e.g., Tinubin), fluorescent brightening agents (e.g., Leucophor), dyes, pigments, couplers, anti-foggants (e.g., l-phenyl-5-mercaptotetrazole), hardeners (e.g., formalin and mucochloric acid), coating aids (e.g., saponin and sodium alkylbenzenesulfonates), sensitizers, developers and stabilizers, whereby the softener can not only display its primary'effects but also can have other functions. For example, a softener containing an ultraviolet I absorber can prevent the optical fading of photographic image, and a softener containing an anti-- foggant can prevent the pressure fog of light sensitive photographic material by liberating the anti-foggant due to breakage of film walls when a high pressure is applied thereto.

The softener of the present invention scarcely brings about such detrimental effect that substances used and by-produced at the time of preparation of the softener migrate into photographic emulsion layers or treating solutions to deteriorate the photographic properties of the resulting light-sensitive material. If there is any fear with respect to this point, the softener may be subjected to purification carried out, for example, in such a manner that the micro capsules are once precipitated by centrifugal separation, freed from the supernatant, washed and then re-dispersed; the micro-capsules are set by use of a gelatin solution as a dispersion medium therefor, and are then finely divided and washed with water; or the micro-capsules are agglomerated and precipitated by use of a salt such as ammonium sulfate or an anionic high molecular compound, freed from the supernatant, washed and then re-dispersed.

The present invention is illustrated in detail below with reference to examples; but the invention is not limited to the examples.

EXAMPLE 1 1O Grams of Epicote 828 (epoxy resin produced by Shell Oil Co.) was dissolved in 30 g. of a mixed oil prepared by mixing tricresyl phosphate and dibutyl phthalate with each other in a ratio of 3:1 which was similar drops came to have a particle size of less than 1 micron. I

The liquid was stirred at room temperature for 2 hours and then at 45C. for about 8 hours to obtain a dispersion of micro-capsules having an average particle size of 0.5 micron (maximum particle size 1 micron) which contained the mixed oil of tricresyfphosphate and dibutyl phthalate in the film walls of an insoluble solid polymer formed at the interface of the liquid drops by the reaction of Epicote 828 with Epicure U.

A silver iodobromide emulsion which contains 120 g. of gelatin per mole of silver and 3 mole percent of silver iodide was subjected to chemical aging and then equally divided into two emulsions. One emulsion was incorporated with the micro-capsule dispersion obtained according to the aforesaid method so that the amount of the micro-capsules became 20 percent by weight based on the weight of gelatin, and then sufficiently stirred. The emulsion incorporated with the micro-capsules and the emulsion incorporated with no micro-capsules were individually coated uniformly on Relative Pressure Radius of speed I resistance curvature (Weight of a (20C weight which 209? RH) formed pressure fog) Emulsion incorporated lOO 40 g. 2 m. with ho micro-capsules Emulsion incorporated 104 g. 6 m. with micro-capsules As seen in the above table, the emulsion incorporated with micro-capsules gave a light-sensitive material which had been improved in elasticity without deterioration in speed, enhanced in pressure resistance and decreased in curling property.

EXAMPLE 2 3 Grams of an ultraviolet absorber (Tinubin) was dissolved in the mixed oil used in Example 1. Subsequently, the mixed oil was treated in the'same manner as in Example 1 to obtain a dispersion of microcapsules containing the ultraviolet absorber. This micro-capsule dispersion and the micro-capsule dispersion obtained in Example 1 were mixed with each other in a ratio of 2:1, and the resulting mixture was incorporated into each layer of a color printing paper so that the amount of the micro-capsules became 20 percent by weight based on the weight of gelatin. As the result, the printing paper was improved in elasticity enhanced in pressure resistance and greatly decreased in curling property, like in Example 1, and the resulting image was markedly enhanced in light fastness.

EXAMPLE 3 3 Grams of an oil-soluble fluorescent brightening agent of the formula,

t-CtHo was dissolved in the mixed oil used in Example 1. Subsequently, the mixed oil was treated in the same manner as in Example 1 to obtain a dispersion of microcapsules containing the fluorescent brightening agent. This micro-capsule dispersion was incorporated into each layer of a color printing paper so that the amount of the micro-capsules became 20 percent by weight based on the weight of gelatin. As the result, the printing paper was improved in elasticity, enhanced in pressure resistance and greatly decreased in curing property, like in Example 1, and the surface of the resulting image was markedly enhanced in optical brightness.

EXAMPLE 4 3 Grams of a curing agent Epicure U (amine addition product of epoxy resin, produced by Shell Oil Co.) was dissolved in a mixed solution comprising cc. of pure water and 15 g. of glycerin. Subsequently, the mixed solution was dropped into 200 cc. of a4 percent-polyvinyl acetate toluene solution containing 12 g. of Epicote 828 (epoxy resin produced by Shell Oil Co.) with vigorous stirring at room temperature to form fine drops. The resulting liquid was further subjected to ultrasonic dispersion so that the liquid drops came to have a particle size of less than 1 micron. The liquid was stirred at room temperature for 2 hours and then at 45C. for about 8 hours to obtain a dispersion of micro-capsules containing the mixed solution of water and glycerin in the film walls of an insoluble solid polymer formed at the interface of liquid drops by the reaction of Epicure U with Epicote 828. This micro-capsuledispersion was subjected to centrifugal separation, whereby 38 g. of micro-capsules having an average particle size of 0.5 micron (maximum particle size 1 micron) were obtained.

A silver iodobromide emulsion containing 120 g. of gelatin per mole of silver and 3 mole percent of silver iodide was subjected to chemical aging and then equally divided into two emulsions. One emulsion was incorporated with the micro-capsules obtained according to the aforesaid method so that the amount of the micro-capsules became percent by weight based on the weight of gelatin. and then subjected to ultrasonic dispersion. The emulsion incorporatedwith the microcapsules and the emulsion incorporated with no microcapsules were individually coated uniformly on a subbed polyethylene terephthalate film base of 0.18 mm. in thickness so that the amount of silver became 50 mg/ l 00 cm and then dried to prepare two samples. These samples were measured in relative speed, pressure resistance and radius of curvature to obtain such results as shown in the following table.'

micro-capsules As seen in the above table, the emulsion incorporated with micro-capsules gave a light-sensitive material which had been improved in elasticity without deterioration in speed, enhanced in pressure resistance and decreased in curling property.

EXAMPLE 5 The micro-capsules obtained in Example 4 were incorporated into each layer of a color printing paper so that the amount of the micro-capsules became 25 percent by weight based on the weight of gelatin. As the result, the printing paperwas improved in elasticity, enhanced in pressure resistance and greatly decreased in curling property, like in Example 4, and could be prevented from excessive drying at the time of drying by use of a ferrotype drier.

EXAMPLE 6 l0 Grams of Desmodur N-75 (polyisocyanate compound produced by Bayer Co.) was dissolved in 30 g. of a mixed oil prepared by mixing tricresyl phosphate and dibutyl phthalate with each other in a ratio of 3:1. Subsequently, the mixed oil was dropped into 100 cc. of a 5 percent aqueous polyvinyl alcohol solution with vigorous stirring at 'room temperature to form fine drops. The resulting liquid was further subjected to ultrasonic dispersion so that theliquid drops came to have a particle size of less than 1 micron. Into the thus formed dispersion was dropped with stirring at room temperature over a period of about 2 hours 100 cc. of an aqueous solution containing 3 g. of a curing agent Epicure U (amine addition product of epoxy resin, produced by Shell Oil Co.). Thereafter, the dispersion was further stirred at 40C. for 3 hours to obtain a dispersion of micro-capsules having an average particle size of 0.4 micron (maximum particle size 0.8 micron) which contained the mixed oil of tricresyl phosphate and dibutyl phthalate in the films walls of an insoluble solid polymer formed at the interface of liquid drops by the reaction of Desmodur N-75 with Epicure U. Using the thus obtained micro-capsule dispersion, the same tests as in Example 1 were effected, whereby substantially the same results as in Example 1 were observed.

What we claim is:

1. A process for preparing a light-sensitive silver halide photographic material comprising, as a softener, liquid-containing fine capsules, which comprises preparing an aqueous liquid composed mainly of a first reactant and a water-immiscible liquid composed mainly of a second reactant capable of forming a polymer by reaction with said first reactant, dispersing as fine drops either one of said liquids into the other liquid to form a polymer according to polycondensation reaction of said first reactant with said second reactant which takes place at the interface between the two liquids, so that the surfaces of said fine drops are coated with the thus formed polymer, incorporating the resulting fine capsules into a gelatinous silver halide emulsion, and coating the total emulsion on a base.

2. A photographic material comprising at least a base and gelatinous emulsion layer thereon, wherein said gelatinous emulsion layer comprises, as a softener fine capsules having an outer boundary surface comprising an interfacially polymerized polymer of at least two mutually reactive polycondensable monomers, said a water-immiscible liquid composed mainly of a second reactant capable of forming a polymer by reaction with said first reactant, and dispersing as fine drops either one of said liquid into the other liquid to form a polymer according to polycondensation reaction of said first reactant with said second reactant which takes place at the interface between the two liquid, so that the surfaces of said fine drops are coated with the thus formed polymer. 

1. A PROCESS FOR PREPARING A LIGHT-SENSITIVE SILVER HALIDE PHOTOGRAPHIC MATERIAL COMPRISING, AS A SOFTENER, LIQUIDCONTAINING FINE CAPSULES, WHICH COMPRISES PREPARING AN AQUEOUS LIQUID COMPOSED MAINLY OF A FIRST REACTANT AND A WATERIMMISCIBLE LIQUID COMPOSED MAINLY OF A SECOND REACTANT CAPABLE OF FORMING A POLYMER BY REACTION WITH SAID FIRST REACTANT, DISPERSING AS FINE DROPS EITHER ONE OF SAID LIQUIDS INTO THE OTHER LIQUID TO FORM A POLYMER ACCORDING TO POLYCONDENSATION REACTION OF SAID FIRST REACTANT WITH SAID SECOND REACTANT WHICH TAKES PLACE AT THE INTERFACE BETWEEN THE TWO LIQUIDS, SO THAT THE SURFACES OF SAID FINE DROPS ARE COATED WITH THE THUS FORMED POLYMER, INCORPORATING THE RESULTING FINE CAPSULES INTO A GELATINOUS SILVER HALIDE EMULSION, AND COATING THE TOTAL EMULSION ON A BASE.
 2. A photographic material comprising at least a base and gelatinous emulsion layer thereon, wherein said gelatinous emulsion layer comprises, as a softener fine capsules having an outer boundary surface comprising an interfacially polymerized polymer of at least two mutually reactive polycondensable monomers, said capsules being filled with either an aqueous liquid or a water-immiscible liquid.
 3. A photographic material according to claim 2, wherein said capsules are less than about 1 micron in average particle size.
 4. A photographic material according to claim 2, wherein said gelatinous emulsion layer is a light-sensitive photographic layer.
 5. A photographic material according to claim 2, wherein said capsules are obtained by preparing an aqueous liquid composed mainly of a first reactant and a water-immiscible liquid composed mainly of a second reactant capable of forming a polymer by reaction with said first reactant, and dispersing as fine drops either one of said liquid into the other liquid to form a polymer according to polycondensation reaction of said first reactant with said second reactant which takes place at the interface between the two liquid, so that the surfaces of said fine drops are coated with the thus formed polymer. 